fix: address ESLint errors (unused imports, missing newline at EOF)

- src/index.test.tsx: remove unused React, render, @testing-library imports
  (sorted imports via simple-import-sort)
- src/index.tsx: add trailing newline (eol-last fix)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/index.test.tsx

@@ -1,7 +1,4 @@
-import React from 'react';
+import { describe, expect, it } from 'vitest';
-import { describe, it, expect } from 'vitest';
-import { render } from '@testing-library/react';
-import '@testing-library/jest-dom';
 
 /**
  * Minimal test to verify the plugin index module loads without throwing.